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Yes, but that's half the fun. Bringing these old boys back to life. Earlier projects have been vintage radios from the '30s to early '60s, mostly old tube jobs. I've restored probably between 60 and 80 of those plus some HH Scott, Fisher, and Dynaco stuff. Below are just a couple. The first...

I removed the transformer today to treat the rust that was beginning to form on it. Each of the four KEP nuts and washer were badly corroded, so those are being pitched and I bought new at the local ACE hardware store. I pulled out the four 1/4" mounting bolts, sanded off the worst of the...

Not quite. The AC voltage adds to the DC voltage at all times. The chart below attempts to show this. In this case the AC voltage is a 2 volt peak-to-peak signal represented by the blue line - max voltage is +1 volt, min is -1 volt. The DC voltage in this case is 1.25 volts represented by...

Zero crossing techniques can be applied for AC voltages which can keep the arcing to a minimum. I just noticed that the spec sheet for the CB I noted above lists a maximum of 32vdc (250vac max), so definitely should not be used for the B+ and B- rails. So for DC to be present in the same wires...

Thanks - good to know.

Same info for the AGX fast acting fuses. Shows that a 5 amp fuse will blow in 1 second with an 8 amp load. For the CB to act in 1 second the load would have to be between 300% (15 amps) to 500% (25 amps) for a 5 amp rated CB.

Here's the trip time for the ones I mentioned from the spec sheet.

Appreciate the input and this is what I'm looking for - pros and cons. Given that they replace slo-blow puts the nail in the coffin for the DC. But for the AC main, I may do it for the reasons I stated above. Interesting what you state concerning arc flash problems, since all the aircraft...

Yes, the caps are STM and they will be replaced. I've ordered replacements from White Oak. With regard to the fuse holders, I am considering replacing them with circuit breakers such as these from Mouser - W28-XQ1B-8 (or 5 amp versions for the B+ and B- legs). The issue is they take a larger...

I'm beginning a WOPL update for this old PL400 (and before I get it in the ear from WOPL Sniffer about why I didn't do it for a PL700, it's because I choose to ;-) ). This one is just starting to suffer from corrosion on all the hardware and the transformer, so first step is to tear it apart...

That answers it! Thanks for doing the search and pointing me in the right direction. Odd scheme, but encodes month and year in the s/n.

Very interesting... Truly looks like it was meant for publication and distribution. This has probably been asked and answered, but what was Phase Linear's method of assigning serial numbers?

Yup, that matches my defective one. Let me send you a PM.

If the guts are good, I'm interested. Mine is cosmetically okay, but one of the previous owners dicked with it and stripped the pivot points. If it's the same type, it should fit. Makes a nice paper holder though.

Have you got another? I'm afraid I need one too.

I'm in need of a VU meter for my PL400 series 1 - 4 fin version. Lights are on the bottom. I'm willing to pay a reasonable price including shipment. Let me know if you have one you're willing to part with. Thanks!

Marcok, I've given some thought to your proposal to add some hot glue or silicone to the sides of the connector. The problem is really that the top of the daughter boards are unsecured - allowing the top to vibrate and consequently put stress on the connector and ultimately the solder...

Following up on my earlier statement that the PL4000 does not have flat response from 20Hz to 20kHz (PL specifications state 20 to 20kHz +/- 0.5dB), I ran a frequency response test on the PL30 Tone Decoder daughter board in my version of the preamp. (Note: I don't have the PL03 Tone Amplifier...

Has anyone come up with a better way to physically stabilize the daughter boards besides using pieces of foam? As long as you don't move them too much, I suspect the current method is okay, but transporting these units must be a nightmare. I'm not too wild about having foam jammed in between...

Great stuff! I appreciate that, Ed. A couple of further notes: 1) I did a paper analysis of the circuitry of the PL30 version of the Tone Amplifier as shown in the schematic. It is the missing RC network that gives the boost to the high frequencies. Without them response is flat at the...